NOTE: Manage Exchange workload can be achieved either by monitoring the health of system resources or by controlling how resources are consumed by individual users (sometimes called user throttling in Exchange Server 2010).

Throttling: Throttling is a part of work load management (WLM) and its functionality is improved in Exchange 2013. This helps to make sure that excessive resource consumption by individual users doesn’t disturb the server performance or the user experience adversely. This also provides:

A way to prevent single-user Denial of Service (DoS) attacks by intelligent traffic shaping interactive usage

System Workload Management:

Controlling how resources are consumed by individual users was also possible in Exchange Server 2010, and this capability has been prolonged for Exchange Server 2013. We have an option to customize the Workload Management settings if required. Components of System WLM are as below:

Throttling Exchange workloads are based on the health of key system resources which protects and manages the consumption of Exchange resources. Exchange workloads may include background services and asynchronous services such as the Microsoft Exchange Mailbox Replication service and the Microsoft Exchange Mailbox Assistance service. As the health of a system resource begins to degrade, the Exchange workloads that rely on that system resource are dynamically throttled to allow Exchange to continue efficient operation. This throttling, known as shaving the peaks, allows users to continue to use resources without experiencing any noticeable performance degradation. Similarly, when system resources are healthy, background workloads are allowed to speed up and fill the valleys in resource usage.

It monitors the health of the following key resources to determine when to throttle workloads

Local server CPU usage

Mailbox database Remote Procedure Call (RPC) latency

Mailbox database replication health

Context indexing age of last notification

Context indexing retry queue size

Workload Classifications

Each Exchange workload (ex: Calendar Synchronization Assistant workload), is assigned a classification and workload policy settings are used for the classification to control both priority and target resource usage.

Exchange workloads can be assigned one of the following classifications:

Urgent

Customer Expectation

Internal Maintenance

Discretionary

Workloads in a higher classification group are given preference as resource health shows signs of degrading. For example, when a resource such as local server CPU reaches high usage, workloads classified as Internal Maintenance may continue to run, while workloads classified as Discretionary may be stopped.

Exchange Workload Management Settings:

When Exchange 2013 is installed, there is a single default Throttling policy called GlobalThrottlingPolicy which has the Global Scope. This Global Policy defines the baseline default throttling settings for every new and existing user in your organization and it is not recommended to modify Global Throttling policy. There are other user throttling policies with Organization (create to manage all users in the organization) and Regular (create to manage specific set of users in the organization) Scope.

NOTE: The customized new throttling policies should have the different throttling setting than in the GlobalThrottlingPolicy settings.

By making changes to the GlobalOverrideWorkloadManagementPolicy object, administrator can override the default workload management policy settings for all servers in the organization. Or can create custom workload management policies on server basis.

Points needs to be considered before creating the custom policies:

Workload management policy settings that are applied using the GlobalOverrideWorkloadManagementPolicy policy will take precedence over the settings in the DefaultWorkloadManagementPolicy_<Server Version> policy

Workload management policy settings that are applied using a custom workload management policy take precedence over any settings that are configured using the Default policy (DefaultWorkloadManagementPolicy_<Server Version>) or the GlobalOverride policy (GlobalOverrideWorkloadManagementPolicy)

Although, you can modify the workload management settings for your entire organization by editing a default workload management policy, but is not recommended as the settings within default workload management policies can be overwritten by the installations of Exchange service packs or other Exchange updates if those packages include changes to workload management policy settings.

NOTE: The *-ResourcePolicy, *-WorkloadManagementPolicy and *-WorkloadPolicy system workload management cmdlets have been deprecated. System workload management settings should be customized only under the direction of Microsoft Customer Service and Support.